Final answer:
Artificial sweeteners like saccharin and aspartame taste sweet by binding to taste receptors, but they are not used by the body for energy because they are either excreted unchanged or used in such small quantities that they do not contribute significantly to caloric intake.
Step-by-step explanation:
Artificial sweeteners are designed to taste sweet, similar to sugar, but they are not metabolized by the body for energy. These sweeteners , like saccharin, aspartame, and sucralose, are much sweeter than sucrose (table sugar) and can be used in smaller quantities. For example, saccharin is about 300 times sweeter than sucrose, which means it can be used in very small amounts to achieve the desired level of sweetness without adding calories.
Our taste buds have receptors that are activated by sweet substances. Artificial sweeteners bind to these G protein -coupled receptors, mimicking the taste of sugar. However, unlike sugar, they are not digested and used as energy. Saccharin, for instance, passes through the body unchanged, and thus it adds no calories. Aspartame, another sweetener , is a methyl ester of a dipeptide made from amino acids aspartate and phenylalanine. It is broken down to its amino acid components and methanol, but still does not contribute to caloric intake significantly.
Artificial sweeteners are beneficial for individuals who must manage their carbohydrate intake, such as people with diabetes. They have been widely studied and are considered safe for consumption by healthy individuals in moderate amounts, though there are specific considerations for individuals with conditions like phenylketonuria (PKU).